Flow control devices (e.g. valves) are commonly used in wells for controlling fluid communication between different well regions, between a well region and the inside of a tool string, or between different regions of a tool string. Flow control devices can be controlled by one of many different mechanisms, including hydraulic mechanisms, electrical mechanisms, fiber optic mechanisms, and so forth. Hydraulic, electrical, optical, or other types of signals are often communicated through a control line (or multiple control lines) to actuate the flow control device.
A flow control device can be actuated between an open position and a closed position. Often, flow control devices also have at least one intermediate position (a choke position) between the open and closed position in which the flow control device is partially open.
Usually, it is difficult to accurately determine (from a remote location such as from the earth surface of the well) whether a flow control device has been successfully actuated. Feedback regarding actuation of a flow control device is typically provided by detecting one or more indirect indications of flow control device actuation, including (1) detecting the volume of hydraulic fluid pumped into or returned from a control line; (2) detecting a change in well flow volumes either at the surface or at a downhole location detected by a downhole measurement device; and (3) detecting downhole pressure or temperature measurements near the flow control device.
The latter two detection techniques can be inaccurate when actuation of the flow control device causes relatively small changes in the flow condition, such as in a situation where multiple zones are producing and the fluid flow from the multiple zones are commingled, or where a flow control device has many intermediate positions such that actuation of a flow control device between two successive positions causes a small change in fluid flow.
The inability to accurately detect actuation of a flow control device means that well personnel cannot be sure that the flow control device has been actuated. This uncertainty may cause well personnel to incorrectly assume that a flow control device has been actuated, when in fact the flow control device has not; or vice versa.